Hair straightener

ABSTRACT

The present invention relates to a hair straightener ( 10 ) comprising:—a first jaw ( 12 ) having a first plate ( 16 );—a second jaw ( 14 ) having a second plate ( 18 );—a hinge ( 20 ) coupled to the first and second jaw ( 12, 14 ) to permit a user to swivel at least one of the jaws ( 12, 14 ) around a hinge axis ( 22 ) between an open and a closed position;—a heater for heating at least one of the first and the second plate ( 16, 18 ); and—an operating lever ( 26 ) to regulate a clamping pressure between the first jaw ( 12 ) and the second jaw ( 14 ), the operating lever ( 26 ) being coupled to the first jaw ( 12 ) via a first spring element ( 28 ) and pivoted to permit the user to swivel the operating lever ( 26 ) relative to the first jaw ( 12 ) around the hinge axis ( 22 ) or around an axis parallel thereto.

FIELD OF THE INVENTION

The present invention relates to the field of hair care and hair styling. In particular, the present invention relates to a hair straightener for straightening hairs.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 5,223,694 discloses a hair styling iron for selectively effecting hair straightening or curling, which includes a generally circular cross-section electrically heated barrel. A tongue is movable relative to the barrel for selectively clamping a strand of hair between the tongue and the peripheral surface of the barrel for curling hair wound therearound.

Hair styling appliances are generally known and include hair curlers, hot combs and hair straighteners. Hair straighteners, which are sometimes also referred to as hair irons, are used to straighten the hairs. These hair straighteners usually comprise two jaws which are hinged in order to pinch a strand of hair. Each jaw comprises a structured or unstructured plate, one or both of which are heated directly or indirectly by means of a heater. An additional heat control system may be applied to regulate the temperature of one or both plates. The hair straightener is usually either powered by main supplied electricity or battery-driven.

To straighten the hairs a strand of hair is inserted into the hair straightener, wherein it is pinched between the two heated plates. The two jaws of the hair straightener may thereto be moved from an open position to a closed position. A hinge is usually provided at the rear end of the hair straightener. This hinge couples the two jaws with each other to permit a user to swivel at least one of the jaws around a hinge axis between the open and the closed position.

Several parameters have a big influence on the efficiency of the hair straightening device. One of the most important parameters beside a correct temperature is the clamping force with which the two jaws of the hair straightener are pressed against each other. The clamping force squeezes the hairs between the two plates. With the amount of clamping force the user regulates the pulling force of the hairs. To get a satisfying hair straightening result a correctly adapted amount of pulling force is of utmost importance. If the pulling force is too low, the hairs will not become straight and the heat transfer from the two plates to the hair may become inefficient. If the pulling force is too high, this may hurt the user and the hairs can be damaged.

Most of the prior art hair straightening devices only allow a manual adaptation of the pulling/clamping force by the user him-/herself. To get the right pulling force on the hairs, the user has to practice and learn how strong to press the two jaws of the straightener against each other. Applying the “correct” amount of clamping/pulling force may sometimes be difficult, especially for inexperienced users.

DE 197 50 119 A1 discloses a hair straightener that allows to limit the clamping force to a maximum value. At least one of the two plates are spring-loaded in order to regulate the clamping force. As soon as the two plates contact each other, the clamping force may be increased until the spring-loaded plate reaches the spring stop. The above-mentioned learning process for the user can therefore be eliminated, since it is ensured that the clamping force may not be increased beyond a certain maximum. However, as the spring system should not take up too much room, the travel between a first contact of the plates and the point where the maximum force is reached is only about 1 mm within the solution provided in DE 197 50 119 A1. This short way makes the system very sensitive to the amount of hairs which are clamped in between the two plates. If the hair strand has a thickness of e.g. 1 mm (which is common), the maximum force will be exceeded if the user presses too strong.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide an alternative hair straightener that allows to more easily and more intuitively apply a “correct” clamping force between the two touching plates. In particular, it is an object to provide a hair straightener, wherein the regulation of the clamping force between the two plates is more practicable for the user.

The above-mentioned problem is solved by a hair straightener that comprises:

a first jaw having a first plate;

a second jaw having a second plate;

a hinge coupled to the first and second jaw to permit a user to swivel at least one of the jaws around a hinge axis between an open and a closed position;

a heater for heating at least one of the first and the second plate; and

an operating lever to regulate a clamping pressure between the first jaw and the second jaw, the operating lever being coupled to the first jaw via a first spring element and pivoted to permit the user to swivel the operating lever relative to the first jaw around the hinge axis or around an axis parallel thereto.

Preferred embodiments of the invention are defined in the dependent claims.

In contrast to prior art hair straightener devices, the hair straightener device according to the present invention comprises an extra operating lever that facilitates to regulate the clamping pressure between the two plates. The presented hair straightener does not only comprise two levers but comprises three levers on total. Each jaw, the first jaw and the second jaw, builds a lever that is coupled to the hinge, which is preferably arranged at a rear end of the jaws. Similar as in prior art devices this permits the user to swivel at least one of the jaws around the hinge axis between the open and closed position of the hair straightener. The operating lever is provided in addition thereto. This operating lever forms a kind of third lever that is preferably also coupled to the hinge and pivotable around the hinge axis.

The user may therefore grasp the hair straightener with one hand, for example by pushing the operating lever with the thumb while grasping the second jaw with the other four fingers. In this way the two jaws can be swiveled relative to each other until the two plates contact each other. Since a first spring element is arranged between the first jaw and the operating lever, the user may then increase the pressure between the two plates by swiveling the operating lever relative to the first jaw against the spring force of the first spring element. The user may thus regulate the clamping force very easily by pressing the operating lever against the spring force of the first spring element and thereby pressing the operating lever further towards the first jaw.

The spring force of the first spring element limits the force transferred to the hairs by the two plates to a certain, optimum force. The user does not have to learn how strong he/she has to clamp the hairs in between the two plates, since the optimal clamping force is already predetermined by the system itself.

Since the first spring element is placed between the operating lever and the first jaw, it has a spring travel that starts at the point where the two plates contact each other in the closed position and ends when the operating lever is completely pressed against the spring force towards the first jaw. This spring travel may be in a range of 10 mm, which results in an absolutely tolerant system regarding the thickness of a hair strand that is straightened with the hair straightener.

In contrast to the hair straightener provided in DE 197 50 119 A1 a ten times longer spring travel may be realized. This allows to increase the amount of hairs that are concurrently worked on with the hair straightener. The increased spring travel also facilitates the regulation of the clamping force between the two plates.

According to an embodiment of the present invention the first spring element exerts a spring force that spaces the operating lever apart from the first jaw. The first spring element can be realized as any kind of spring element, e.g. a pneumatic, hydraulic or mechanical spring element. The easiest and most preferred solution is the usage of a mechanical spring element. Preferably a metal spring is used, since metal springs almost show no relaxation over time.

According to a further embodiment of the present invention the first spring element is a mechanical spring exerting the spring force along a spring axis that is arranged transverse to the hinge axis and transverse to a longitudinal axis of the first jaw. The longitudinal axes of both jaws run radially outward from the hinge axis. These longitudinal axes are preferably arranged perpendicular to the hinge axis. The spring axis of the first spring element is preferably arranged perpendicular to the longitudinal axis of the first jaw as well perpendicular to the hinge axis. In other words, the spring axis preferably extends substantially parallel to the circumferential direction of the hinge, i.e. substantially parallel to the closing direction along which the two jaws are moved towards each other when bringing the hair straightener (the two jaws) in the closed position.

The first spring element is preferably arranged near the front end of the operating lever. At the opposite rear end the operating lever is coupled to the hinge axis. Since the length of the operating lever is preferably in a range of 30 to 70% of the length of the jaws, a comparatively long lever arm of the operating lever is established. The longer the lever arm of the operating lever, the easier it is for the user to regulate the clamping force.

According to a further embodiment of the present invention the hair straightener further comprises a second spring element arranged between the two jaws that forces the two jaws toward the open position, wherein a position of the first spring element relative to the second spring element and/or a first spring constant of the first spring element relative to a second spring constant of the second spring element is chosen such that a force exerted by the first spring element spacing the operating lever apart from the first jaw is higher than a force exerted by the second spring element forcing the two jaws toward the open position.

The second spring element is preferably arranged near, at or around the hinge axis. It may be either realized as a linear coil spring or as a torsion spring that forces the two jaws toward the open position. If the jaws are not actively pressed together, the jaws will therefore always remain in the open position, which is an important security feature.

The fact that the force exerted by the first spring element spacing the operating lever apart from the first jaw is higher than the force exerted by the second spring element spacing the two jaws apart from each other has the following advantages: Pinching the operating lever and the second jaw together first results in a movement of the two jaws relative to each other until the two plates contact each other. During this movement the operating lever will not or only slightly move relative to the first jaw, as the spring force between these two elements is higher. The operating lever will only move/swivel with respect to the first jaw after the contact of the two plates, if the operating lever is pressed further against the first jaw. The user may therefore easily recognize the moment when the two plates contact each other, so that further swiveling the operating lever results in an increased clamping pressure. The regulation of the clamping force is therefore easy to handle for the user.

The aforementioned effect may, for example, be realized by setting the first spring constant larger than the second spring constant. It may also be realized by arranging the second spring closer to the hinge axis than the first spring, which is preferably always the case. Due to the larger mechanical lever between the hinge axis and the first spring element compared to the mechanical lever between the hinge axis and the second spring element less force is effectively needed to press the two jaws together than to press the operating lever against the first jaw.

Preferably, the operating lever is pivoted to permit the user to swivel the operating lever relative to the first jaw between a start position, in which the operating lever and the first jaw are spaced apart from each other, and an end position, in which the first spring element is compressed and the operating lever is pressed onto an upper side of the first jaw.

According to a preferred embodiment of the present invention a rear side of the operating lever, which faces substantially towards the upper side of the first jaw, has a positive fit with said upper side of the first jaw in the end position. The rear side of the operating lever is thus adapted to the shape of the upper side of the first jaw. The operating lever may therefore butt against the first jaw in the end position. Due to the corresponding shapes of the operating lever and the first jaw, a relatively space-saving arrangement is realized.

According to a further embodiment of the present invention the operating lever comprises at least one through hole that serves as access to an operating button of the hair straightener which is arranged on the upper side of the first jaw. This operating button may either be an on/off button or a button to regulate the heater. The at least one through hole within the operating lever allows to operate this button at all times, independent of the position of the operating lever.

According to a further embodiment of the present invention the operating lever comprises at least one stop pin that extends transverse to the hinge axis and transverse to a longitudinal axis of the operating lever, wherein the at least one stop pin is configured to contact an end stop at the second jaw when the operating lever is in its end position. Preferably, the at least one stop pin extends perpendicular to the hinge axis and perpendicular to the longitudinal axis of the operating lever. It preferably runs parallel to the spring axis of the first spring element. Instead of providing only one such stop pin, two stop pins may alternatively be provided. This increases the mechanical stability.

The at least one stop pin is a kind of bar that is arranged at the front end of the operating lever. The at least one stop pin together with the end stop, that is provided at or within the second jaw, allow to exactly define the end position of the operating lever. As soon as the at least one stop pin contacts the end stop at the second jaw, a further movement of the operating lever relative to the other two jaws/levers is not possible anymore. This means that not only the end position is exactly defined but also the maximum clamping force with which hairs can be pinched between the two jaws. A too high pressure, that could damage the hairs, is not even possible. The inventors have therefore found a mechanism to limit the force transfer to the hairs to a predetermined, optimum force. This optimum force cannot be exceeded.

The above-mentioned end stop is preferably arranged within a recess in the second jaw. This recess within the second jaw is preferably arranged at the side of the second jaw that faces towards the first jaw.

According to a further embodiment the first jaw comprises at least one opening that extends transverse to the hinge axis and the longitudinal axis, wherein the at least one stop pin is guided through said at least one opening.

Such a guidance further increases the mechanical stability of the connection between the operating lever and the first jaw. In case of two stop pins, which are arranged on the operating lever, each stop pin is guided in a separate opening within the first jaw.

According to a further embodiment of the present invention the at least one stop pin comprises a length adjustment mechanism for adjusting a length of the stop pin. Such a length adjustment allows to regulate the stop point of the operating lever. Adjusting the stop point of the operating lever also means an adjustment of the maximum clamping force that may be reached between the two heating plates. The at least one stop pin may, for example, be designed as a telescopic bar that allows to easily adjust its length. The length of the stop pin could e.g. be adjusted depending on the hair thickness as well as depending on the styling needs. Such an adjustment further increases the flexibility of the hair straightener and makes it adaptable to the specific personal needs.

According to a further embodiment of the present invention the at least one of the first plate and the second plate has a spring system that comprises an adjustment screw for adjusting a spring tension and/or a spring excursion of the spring system.

The two heating plates may therefore be spring-loaded in addition to the flexibility that is provided by the above-described first spring element. The adjustment screw allows a further adjustment of the clamping force that is established between the two heating plates. Both heating plates may be equipped with such an adaptable spring system.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. In the following drawings

FIG. 1 shows a perspective view of a hair straightener according to the present invention;

FIG. 2 shows different top views (FIG. 2 a, b) and an enlarged view (FIG. 2 c) of the hair straightener shown in FIG. 1;

FIG. 3 shows a perspective view of an operating lever that is used in the hair straightener according to the present invention; FIG. 4 shows a further detail of the hair straightener according to the present invention; and

FIG. 5 shows different side views for illustrating the working principle of the hair straightener according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an embodiment of the hair straightener according to the present invention. The hair straightener is therein in its entirety denoted with reference numeral 10.

The hair straightener 10 comprises two jaws, a first jaw 12 and a second jaw 14. The first and the second jaw 12, 14 build the major housing parts of the hair straightener 10. Each jaw 12, 14 comprises a plate 16, 18. The first plate 16 is arranged at the first jaw 12. The second plate 18 is arranged at the second jaw 14. Both plates 16, 18 are also referred to as heating plates 16, 18.

During operation of the hair straightening device 10 the hairs are, hair strand by hair strand, pinched between the two plates 16, 18. The hair straightener 10 thereto comprises a hinge 20 that is coupled to the first jaw 12 and the second jaw 14. This hinge 12 is usually arranged at a rear end 24 of the two jaws 12, 14. The hinge 20 permits a user to swivel/pivot at least one of the jaws 12, 14 around a hinge axis 22. In this way the two jaws 12, 14 can be swiveled/pivoted between an open and a closed position. It is to be noted that FIG. 1 illustrates the open position of the hair straightener 10.

At least one of the first and the second plate 16, 18 is heated by a heater (not shown). This heater is preferably integrated into the housing parts 12, 14 (jaws) of the hair straightener 10. The heater can be realized in many different ways. Usually an inductive heater is used. This heater can be either powered by main supplied electricity or battery driven.

The hairs only need to be pinched/clamped between the two plates 16, 18 in order to straighten them. The main parameter influencing the straightening performance is the temperature that is generated by the heating plates 16, 18 as well as the clamping force with which the heating plates 16, 18 are pressed together. The temperature is preferably either regulated manually or automatically using a temperature control system. In order to guarantee a “correct” clamping force, the hair straightener 10 according to the present invention further comprises a so-called operating lever 26. This operating lever 26 acts as a kind of force limiter that limits the clamping force applied between the two plates 16, 18 to a predetermined maximum value. The risk of applying a too high clamping force and thereby eventually damaging the hairs can be overcome in this way.

The operating lever 26 has a similar shape as the two jaws 12, 14, which both also have the shape of a lever. The operating lever 26 is preferably shorter than the levers of the two jaws 12, 14. A length of the operating lever 26 can e.g. be in a range of 30-70% of the length of each jaw 12, 14. The operating lever 26 is pivotable relative to the first jaw 12. The operating lever is thereto hinged at the hinge 20. This allows a user to swivel/pivot the operating lever 26 relative to the first jaw 12 around the hinge axis 22. However, it shall be noted that the operating lever 26 does not necessarily need to be hinged at the same hinge 20 as the two jaws 12, 14. It may be also coupled with a further hinge that runs parallel to the hinge 20.

The operating lever 26 is furthermore coupled to the first jaw 12 via a spring element 28. As it may be seen in the enlarged view illustrated in FIG. 2 c, the spring element 28 is arranged at a front end 30 opposite the rear end 24 of the operating lever 26. The spring element 28, which is also denoted as first spring element 28, is preferably realized as a mechanical spring, e.g. a metal spring. The first spring element 28 contacts a stud 34 that protrudes from the operating lever underneath its top surface. This stud extends perpendicular to the longitudinal axis 36 of the operating lever 26 as well as perpendicular to the hinge axis 22. The first spring element 28 is arranged coaxially to the stud 34. It extends along a spring axis 32 that is perpendicular to the longitudinal axis 36 and the hinge axis 22. The spring element 28 exerts a spring force along the spring axis 32. This spring force spaces the operating lever 26 and the first jaw 12 apart from each other.

The working principle of the hair straightener 10 and the operating lever 26 is schematically illustrated in FIG. 5. As already mentioned before, the first jaw 12 may be swiveled/pivoted relative to the second jaw 14 around the hinge axis 22. The operating lever 26 may, similar thereto, be swiveled/pivoted relative to the first jaw 12 around the hinge axis 22. The user may therefore swivel/pivot the operating lever 26 relative to the first jaw 12 between a start position and an end position. In the start position the operating lever 26 and the first jaw 12 are spaced apart from each other (see e.g. FIG. 5 a). In the end position of the operating lever 26 the spring element 28 is compressed and the operating lever 26 is arranged closer to the first jaw 12 as in the start position or even pressed onto an upper surface 38 of the first jaw 12.

In order to press the two heating plates 16, 18 together, a user holds the hair straightener 10 in one hand by e.g. touching the operating lever 26 with the thumb and holding the second jaw 14 with the other four fingers, or vice versa.

FIG. 5 a shows the open position of the first and second jaw 12, 14. This is the regular position of the hair straightener 10 when no pressure is exerted to it by the user's hand. For security reasons the two jaws 12, 14 shall always be forced towards the open position. This is guaranteed by a second spring element (not shown) that is arranged near the rear end 24. This second spring element may e.g. be realized as a kind of torsion spring that is arranged around the hinge axis 22. The second spring element forces the two jaws 12, 14 toward the open position.

The position of the first spring element 28 relative to the second spring element and/or a first spring constant of the first spring element 28 relative to a second spring constant of the second spring element is preferably chosen such that a force exerted by the first spring element 28 spacing the operating lever 26 apart from the first jaw 12 is higher than a force exerted by the second spring element forcing the two jaws 12, 14 toward the open position. This may be realized by setting the first spring constant larger than the second spring constant. It may also be realized by arranging the second spring closer to the hinge axis 22 than the first spring element 28, which is preferably always the case. Due to the larger mechanical lever between the hinge axis 22 and the first spring element 28 compared to the mechanical lever between the hinge axis 22 and the second spring element less force is effectively needed to press the two jaws 12, 14 together than to press the operating lever 26 against the first jaw 12.

When pressing the operating lever 26 toward the second jaw 14, this results first in a movement of the two jaws 12, 14 relative to each other (toward the closed position). The operating lever 26 will during this movement not or only slightly move relative to the first jaw 12. FIG. 5 b illustrates the end of the described movement. Therein the two jaws 12, 14 are in the closed position, such that the two heating plates 16, 18 contact each other. The operating lever 26 is in this position of the hair straightener 10, however, still in its so-called start position (relative to the first jaw 12).

If the user then further presses the operating lever 26, the operating lever 26 will also move relative to the first jaw 12, as the first spring element 28 will then be compressed until an end stop is reached. FIG. 5 c illustrates this situation. Therein the two jaws 12, 14 are in its closed position and the operating lever 26 is in its end position. If this situation is reached, the clamping force between the two heating plates 16, 18 may not be increased anymore.

In summary this means that there is at first no movement of the operating lever 26 relative to the first jaw 12 (only a movement of the two jaws 12, 14 relative to each other). This relative movement between the operating lever 26 and the first jaw 12 only starts as soon as the two jaws are pressed together and the plates 16, 18 contact each other. By then further pressing the operating lever 26, the pressure between the plates 16, 18 may be further increased until the operating lever 26 reaches its end position (see FIG. 5 c). It is to be noted that FIGS. 5 a-c illustrate consecutive situations at consecutive points in time when operating the operating lever 26 in order to press the two plates 16, 18 together.

Since the clamping pressure cannot be increased further as soon as the operating lever 26 reaches its end position, said operating lever 26 acts as a kind of force limiter. In order to mechanically define the end position of the operating lever 26, it preferably comprises two stop pins 40, 40′ (see e.g. FIG. 3). These two stop pins are arranged at the front end 30 of the operating lever 26 and extend perpendicular to the longitudinal direction 36 as well as perpendicular to the hinge axis 22. The two stop pins 40, 40′ are configured to contact end stops 42, 42′ (see e.g. FIG. 4) when the operating lever 26 is in its end position (illustrated in FIG. 5 c). The two end stops 42, 42′ are arranged within separate recesses in the second jaw 18. The two stop pins 40, 40′ together with the end stops 42, 42′ therefore limit the movement of the operating lever 26 with respect to the other two levers 12, 14.

The length of the movement travel may be regulated by adapting the length of the stop pins 40, 40′. According to an embodiment of the present invention the two stop pins 40, 40′ may thereto comprise a length adjustment mechanism for adjusting the length of the stop pins 40, 40′. This may be e.g. realized by a telescopic mechanism (not shown).

It shall be noted that it is also conceivable to apply only one stop pin 40 and only one end stop 42 without leaving the scope of the present invention. Alternatively, also more than two stop pins 40, 40′ and more than two end stops 42, 42′ may be used.

In order to further stabilize the movement of the operating lever 26, the two stop pins 40, 40′ are preferably guided within a mechanical guidance that is arranged within the first jaw 12. Two openings 44, 44′ within the first jaw 12 (see e.g. FIGS. 1 and 5 a) serve as mechanical guidance. The two openings 44, 44′ also extend perpendicular to the hinge axis 22 and perpendicular to the longitudinal axis 36 of the operating lever 26. Each stop pin 40, 40′ is separately guided in one of these two openings 44, 44′. A guidance of the two stop pins 40, 40′ through the openings 44, 44′ allows to realize a relatively space-saving arrangement.

A further feature of the operating lever 26 may be seen in FIG. 3. The operating lever 26 comprises at least one through hole 46 that serves as access to an operating button 48 of the hair straightener 10, which is arranged on the upper side 38 of the first jaw 12. This at least one through hole 46 therefore allows to operate the device 10 independent of the position of the operating lever 26. As it can be seen in FIG. 2 a, a button 48 may for example be pressed through the through hole 46, such that the hair straightener 10 can be switched on and off in any position of the operating lever 26.

The inventors of the present invention have found a solution that allows to easily adjust the clamping pressure between the two heating plates. The extra operating lever that is provided according to the present invention acts as a kind of force limiter and at the same time allows to manually regulate the clamping force. The handling of the hair straightener according to the present invention is therefore very easy and practicable for the user. A learning process for the user to find the optimal clamping force is not necessary anymore, since this is predetermined through the above-described operating lever system.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope. 

1. Hair straightener comprising: a first jaw having a first plate ;. a second jaw having a second plate a hinge coupled to the first and second jaw to permit a user to swivel at least one of the jaws around a hinge axis between an open and a closed position; a heater for heating at least one of the first and the second plate; and characterized by an operating lever to regulate a clamping pressure between the first jaw and the second jaw, the operating lever being coupled to the first jaw via a first spring element and pivoted to permit the user to swivel the operating lever relative to the first jaw around the hinge axis or around an axis parallel thereto.
 2. Hair straightener according to claim 1, wherein the operating lever is pivoted at the hinge to permit the user to swivel the operating lever relative to the first jaw around the hinge axis.
 3. Hair straightener according to claim 1, wherein the first spring element exerts a spring force that spaces the operating lever apart from the first jaw.
 4. Hair straightener according to claim 2, wherein the first spring element is a mechanical spring exerting the spring force along a spring axis that is arranged transverse to the hinge axis and transverse to a longitudinal axis of the first jaw.
 5. Hair straightener according to claim 1, further comprising a second spring element arranged between the two jaws that forces the two jaws toward the open position, wherein a position of the first spring element relative to the second spring element and/or a first spring constant of the first spring element relative to a second spring constant of the second spring element is chosen such that a force exerted by the first spring element spacing the operating lever apart from the first jaw is higher than a force exerted by the second spring element forcing the two jaws toward the open position.
 6. Hair straightener according to claim 1, wherein the operating lever is pivoted to permit the user to swivel the operating lever relative to the first jaw between a start position, in which the operating lever and the first jaw are spaced apart from each other, and an end position, in which the first spring element is compressed and the operating lever is arranged closer to the first jaw as in the start position or pressed onto an upper side of the first jaw.
 7. Hair straightener according to claim 6, wherein a rear side of the operating lever, which faces substantially towards the upper side of the first jaw, has a positive fit with said upper side of the first jaw in the end position.
 8. Hair straightener according to claim 6, wherein the operating lever comprises at least one through hole that serves as access to an operating button of the hair straightener which is arranged on the upper side of the first jaw.
 9. Hair straightener according to claim 6, wherein the operating lever comprises at least one stop pin that extends transverse to the hinge axis and transverse to a longitudinal axis of the operating lever wherein the at least one stop pin is configured to contact an end stop at the second jaw when the operating lever is in its end position.
 10. Hair straightener according to claim 9, wherein the end stop arranged within a recess in the second jaw.
 11. Hair straightener according to claim 9, wherein the first jaw comprises at least one opening that extends transverse to the hinge axis and the longitudinal axis, wherein the at least one stop pin is guided through said at least one opening.
 12. Hair straightener according to claim 9, wherein the at least one stop pin comprises a length adjustment mechanism for adjusting a length of the at least one stop pin.
 13. Hair straightener according to claim 1, wherein at least one of the first plate and the second plate has a spring system that comprises an adjustment screw for adjusting a spring tension and/or a spring excursion of the spring system. 